In radio communication systems it is sometimes beneficial to provide radio users with some information about the received signal quality so that they can get some idea about how far they are away from the transmitting unit and take appropriate action before they are completely out of communication range. Signal quality information can also be used for other purposes such as, determining atmospheric conditions, determining if there are radio frequency "dead spots" in a certain system, etc.
In the case of digital radios, the received digital signals are usually error-corrected as part of the receiving protocol before the digital signals are heard or used by the radio users. Digital radio users cannot tell the signal quality from the error-corrected signal since voice data can still be recovered when the signal quality is poor.
A conventional bit error rate (BER) indicator as used in many well known digital radios, which is based on the output of the error control coding and the feedback error in the recovery loop of the digital receiver, can be used as the signal quality indicator. However, the calculation of the BER takes significant amount of time to calculate which uses up valuable radio processor time. A need thus exists for a simpler and more efficient method and apparatus for measuring digital signal quality.